An idea that I saw brought up in a review of the trailer was that Angela Basset did that monolog to hide the fact that it would actually be Shuri giving that monolog because they thought it would make more sense to kill Queen Romonda because it seems like it would be a big spoiler to basically announce that Shuri also dies in this movie.
Or that scene could take place during the five year period where Shuri and T'Challa were snapped.